LED Solder Alloy Composition for Low-Temperature Bonding
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Solution Overview
Problem
The melting temperature and hardness of solder used in electronic device bonding processes affect the yields and reliability of the devices, with existing solders either damaging components at high temperatures or causing scratches due to low hardness.
Innovation Solution
The use of a solder alloy with a tin and indium or tin and bismuth composition, where the atomic percentage of tin ranges from 40% to 85, reduces the melting point and increases the hardness of the solder, thereby enhancing the bonding process's reliability and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional solder with high melting point is used, then bonding strength is improved, but electronic components may be damaged due to high temperature
Solution Approach 1:
The patent changes the chemical composition parameters of the solder by adding specific elements (In, Ga, Ge, and/or Ag) to the Sn-based solder. This composition modification lowers the melting point from traditional high temperatures to below 200°C, enabling bonding without damaging electronic components while maintaining adequate bonding strength through the specific atomic percentage ranges specified (In: 5-20 at%, Ga: 5-20 at%, Ge: 5-20 at%, Ag: 5-20 at%).
2Object-affected harmful factors
If solder with low melting point is used, then component damage is reduced, but hardness decreases causing scratches
Solution Approach 1:
The patent creates a composite solder material by combining Sn with multiple alloying elements (In, Ga, Ge, and/or Ag) in specific proportions. This composite composition achieves a unique property balance: the low melting point (below 200°C) is maintained through the specific element combination, while the hardness issue is addressed through the synergistic effect of the alloying elements that modify the solder's mechanical properties without sacrificing the low-temperature bonding capability.
3Ease of manufacture
If traditional solder composition is used, then bonding process is simple, but reliability is reduced due to component damage or scratches
Solution Approach 1:
The patent modifies the compositional parameters of the solder to achieve reliable bonding at lower temperatures. By specifying precise atomic percentage ranges for each element (Sn: 50-80 at%, In: 5-20 at%, Ga: 5-20 at%, Ge: 5-20 at%, Ag: 5-20 at%), the invention ensures consistent bonding reliability while maintaining process simplicity through a single-step bonding operation at temperatures below 200°C, eliminating the need for complex multi-stage processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed solder alloy improves the reliability and yield of the electronic device bonding process by reducing the risk of component damage and scratches, while also lowering the melting point to facilitate lower-temperature bonding.
Implementation Method 1
the melting point of the solder may be reduced
Implementation Method 2
increase the hardness of the solder
Data Source
Figure 1~2
Figure 3~4
Figure 5A~5B
AI summary
An electronic device (10) is provided in the present disclosure. The electronic device (10) includes a substrate (102) and a light emitting diode (104). The light emitting diode (104) is bonded to the substrate (102) through a solder alloy (116). The solder alloy (116) includes tin and a metal element M, and the metal element M is one of the indium and bismuth. The atomic percentage of tin in the sum of tin and the metal element M ranges from 60% to 90% in the solder alloy (116).